・eachを一行で書きたい
Areas.each {|area| puts area}
@shops = Shops.where(closed: false).pluck(:area_id).uniq.sort
・pluckの例
<% areas.each do |area| %> <%# 県 %>
<% if @shops.include?(area.id) %>
<%= link_to "#{area.prefecture}", area_path(area.id), class: "dropdown-item" %>
<% else %>
<%= link_to "#{area.prefecture}", area_path(area.id), class: "dropdown-item disabled" %>
<% end %>
<% end %>
【参考記事】
・定番!Rubyでワンライナー書く時の基本テク
https://qiita.com/bash0C7/items/749e60ff770b2e465b5e